In the teaser, Doug looks at a discarded newspaper and says, "Today is June 16, 1956." They then go to meet Alexis at midnight. That would then make it June 17th after that. But all references to the date in the remainder of the show say that it is still June 16th.
Doug and Tony discuss that Beraki's capsule approach is unworkable, and that his tunnel won't work on a person because he hasn't developed the radiation bath. But in "Rendezvous With Yesterday" Doug's explanation of the radiation bath is that it aids tracking, not that it allows time travel.
Most of the Cyrillic signage does not spell anything, it is just gibberish.
When Doug and Tony first meet Alexis, Tony asks, "How did you know our names?", but his lips are not moving.
Even though it is said it takes places in Russia, the opening scene where you can see mosques and minarets is Istanbul, Turkey. It is most famous scene of historical peninsula in Istanbul.